species-area relationship

A well-known strong empirical relationship between the area (A) of a region or patch of habitat and the number of species (S) it contains. Over most spatial scales, a power-law relationship S = cAz provides a good fit to data, with z often around 0.25 for separate sets of regions (known as the island species-area relationship) and 0.15 for nested parts of the same region (known as the continental species-area relationship). The species- area relationship has often been used to estimate the size of an extinction debt (qv) resulting from habitat loss.